In the response surface methodology (RSM), the designed experiment helps create interfactor orthogonality and interpretable response models for the purpose of process and design optimization. However, along with the development of data-recording technology, observational data have emerged as an alternative to experimental data, and they contain potential information on design/process parameters (as factors) and product characteristics that are useful for RSM analysis. Recent studies in various fields have proposed modifications to the standard RSM procedures to adopt observational data and attain considerable results despite some limitations. This paper aims to explore various methods to incorporate observational data in the RSM through a systematic literature review. More than 400 papers were retrieved from the Scopus database, and 83 were selected and carefully reviewed. To adopt observational data, modifications to the procedures of RSM analysis include the design of the experiment (DoE), response modeling, and design/process optimization. The proposed approaches were then mapped to capture the sequence of the modified RSM analysis. The findings highlight the novelty of observational-data-based RSM (RSM-OD) for generating reproducible results involving the discussion of the treatments for observational data as an alternative to the DoE, the refinement of the RSM model to fit the data, and the adaptation of the optimization technique. Future potential research, such as the improvement of factor orthogonality and RSM model modifications, is also discussed.

In this study, an environmentally friendly extraction method for flavonoid compound from Ixora javanica , as a new raw material candidate for herbal medicine and cosmetics, was developed. The objectives of the present work were to provide recommendations for the optimal extraction conditions and to investigate the effects of any extraction parameters on flavonoid yields from the I. javanica flower. The extraction process was performed using deep eutectic solvent (DES) (choline chloride and propylene glycol at molar ratio of 1 : 1) and the ultrasound-assisted extraction method. Both single-factor and response surface analyses using three-level and three-factor Box Behnken designs were conducted to obtain the optimum flavonoid concentrations. The results showed that the optimum extraction conditions for total flavonoids featured an extraction time of 40 min, 25% water content in DES and a solid-to-liquid ratio of 1 : 25 g ml ⁻¹ . An extract obtained under optimum extraction conditions showed higher total flavonoid yields than an ethanolic extract which was used for comparison. Scanning electron microscope images demonstrated that both of the solvents also showed different effects on the outer surface of the I. javanica flower during the extraction process. In summary, our work succeeded in determining the optimum conditions for total flavonoids in the I. javanica flower using a green extraction method.

Due to the different properties of the materials, the fusion welding of dissimilar metals may be difficult. Structural irregularities may form as a result of various phase transformations during welding. Solid-state welding, as opposed to fusion welding, occurs below the melting temperature. As a result of the melting and solidification phenomena that happen in fusion welding, solid-state welding is expected to reduce the potential for phase transformation. This paper describes the use of a rotary friction welding technique to join carbon steel and 304 stainless steel. The purpose of this work is to investigate the characteristics of rotary friction welding (RFW) when joining 304 stainless steel to carbon steels with different carbon contents. Experiments were carried out on the RFW of low- and medium-carbon steels with 304 stainless steel. The investigation was carried out using the Taguchi method of experimental design. The joints’ tensile strengths and microstructures were evaluated. The parameters that had the greatest influence on the tensile strengths of the welding results were identified. The combination of parameters resulting in the greatest tensile strength is also suggested. A microstructural examination of the weldment revealed mechanical mixing and interlocking.

Kombucha coffee is a fermented coffee bean, which is extracted using a combination of bacteria and yeast. Kombucha coffee can be obtained by optimizing the three variables, namely sugar concentration, incubation temperature and duration of fermentation using a response surface methodology (RSM). This study aimed to optimize the three variables that influence the fermentation of Robusta green coffee beans using a kombucha culture to obtain low caffeine content and high levels of chlorogenic acid. RSM calculation was used high-performance liquid chromatography (HPLC) on caffeine and chlorogenic acid that content in kombucha coffee. The results of modeling used a central composite experimental design (CCD). The results of the optimization study showed that the lowest concentration of caffeine and chlorogenic acid was obtained at sugar concentration of 6.77% (b/v), incubation temperature of 25°C and incubation for 18 days. Finally, the fermentation using RSM on kombucha coffee required an additional variable which is the amount of kombucha culture inoculums, as well as the variables of sugar concentration, incubation temperature and duration of fermentation. Key words: Kombucha coffee; caffeine; chlorogenic acid.

Quality and reliability engineering technique are widely used as improvement tools in manufacturing industries, involving the design experiments, quality function deployment (QFD), and survival analysis, focuses on improving the lifecycle of products. However, started at early last decade, some researches in improving the service lifecycle in some service industry consider to implements design of experiment in service industry, followed by other tools such as QFD, and the reliability engineering tools. This research proposed alternatives incorporated quality and reliability engineering methods in evaluating and improving the lifecycle of service. Starting with evaluating the weaknesses of service using SERVQUAL method, finding the improvement plan by implementing QFD, designing the robust service design using Taguchi designed experiment methods, and then implementing survival analysis for ensuring the reliability of designed services. This framework has successfully implemented in designing and evaluating existing airport service system with some recommendation generated in.

— XYZ Group has been expanding their bussiness in various sector i.e., retail, IT consultants, food & beverages, shopping plazas, Japanese restaurants, e-wallets, e-commerce, and expeditions. XYZ Group continues to expand as an action to survive and win the competition. Therefore, XYZ Group’s Recruitment Division plays an important role in business activities. The Human Resource Scorecard is an appropriate method for measuring performance in XYZ Group's recruitment division. The result of Human Resource Scorecard in the XYZ Group Recruitment Division are acquiring 17 Key Performance Indicators (KPI) consisting of financial perspective two KPIs, three customer perspective KPIs, eight operational perspective KPIs, and four strategic perspective KPIs. Performance measurement is carried out by weighting process, followed by performance measurement based on the required data. The measurement results show an overall performance of XYZ’s Recruitment Division is 3,534, which means the performance of the XYZ Group’s Recruitment Division is good. Financial perspective performance gets a value of 2.5 (good enough), customer perspective performance gets a value of 3,831 (good), operational perspective performance gets a value of 3,423 (good), and strategic perspective performance gets a value of 4 (good). Based on the KPI that didn’t reach the target, an action plan was made. In addition to the action plan, performance dashboard and analysis of cause and effect relationships after measurement have been made. Keywords: human resource scorecard, key performance indicator, performance dashboard Abstrak— XYZ Group telah melakukan ekspansi di berbagai bidang, yaitu retail, grocery, IT consultant, food & beverages, shopping plaza, Japanese restaurant, e-wallet, e-commerce, dan ekspedisi. XYZ Group terus melakukan ekspansi sebagai tindakan untuk bertahan dan memenangkan persaingan. Oleh karena itu, Divisi Rekrutmen XYZ Group memegang peranan penting dalam aktivitas bisnis. Human Resource Scorecard menjadi metode yang sesuai untuk melakukan pengukuran kinerja pada divisi rekrutmen XYZ Group. Perancangan Human Resource Scorecard pada Divisi Rekrutmen XYZ Group menghasilkan 17 Key Performance Indicator (KPI), yaitu dua KPI perspektif financial, tiga KPI perspektif customer, delapan KPI perspektif operational, dan empat KPI perspektif strategic. Pengukuran kinerja dilakukan dengan melakukan pembobotan dilanjutkan pengukuran kinerja berdasarkan data yang diperlukan. Hasil pengukuran menunjukkan kinerja keseluruhan sebesar 3,534 yang berarti kinerja Divisi Rekrutmen XYZ Group tergolong baik. Kinerja perspektif financial mendapatkan nilai sebesar 2,5 (cukup baik), kinerja perspektf customer sebesar 3,831 (baik), kinerja perspektif operational sebesar 3,423 (baik), dan kinerja perspektif strategic sebesar 4 (baik). Berdasarkan KPI yang tidak mencapai target dibuat action plan. Selain action plan, dilakukan perncangan performance dashboard dan analisis cause and effect relationship setelah pengukuran. Kata kunci: human resource scorecard, key performance indicator, performance dashboard